Digital imaging devices for capturing image data for display and other processing are well known. Such devices typically include a planar array of sensor elements that detect the intensity of light impinging upon the sensor element. The light intensity is converted to an electrical signal which may be digitized to generate a digital value corresponding to the intensity of light detected by the sensor element. These data values may then be filtered or subjected to other signal processing to reduce artifacts generated by the quantizing of the image data.
Frequently, image data captured by an image device is manipulated to "zoom" or expand the image. That is, the m.times.n sensor element image captured by the device is expanded to an i.times.j image, where i and j are greater than m and n respectively. To zoom an image, the data of an original image array may be moved to an expanded image array as each data value has a corresponding location in the expanded image array. However, there are also numerous array locations in the expanded image array which have no corresponding data value in the original image array. Interpolation methods have been developed to generate data values for each array location having no corresponding data value in the original image array. Typically, these interpolation methods use a mask or other weighting criteria to generate a data value from those data values neighboring the array location for which the data value is being generated. The weighting schemes are typically constructed so that those data values closer to the array location for which a data value is being generated contribute more than the more distant points. Additionally, directional vectors may be determined which indicate that the contribution of data from one area should be weighted more heavily than data from another area that is the same distance from the subject array location. However, if the expansion factor for the expanded image is significant, the quality of the image may be degraded or artifacts generated. Likewise, successive expansions of an image compound the degradation and artifact generation as subsequent zoom images contain proportionally less data values taken directly from the original image array.
What is needed is a method for accurately zooming an original image array to improve the image resolution of expanded images.
What is needed is a method for zooming an original image array after transmission of the original image array in a compressed form that is independent of the compression method used on the original image array.